using Late Binding and early binding in VBA simultaneously - vba

Question

I have a problem as below.
A program is written using early binding in VBA and it only works with all the references connected.
but there are some systems where the references are not connected and when the program is ran on those systems there is a compile error.
so I thought maybe I can use late binding to connect the references but it still shows compile error.
condition is that I cant convert the variables in code to late binding.
Public oPart As Part
Sub CATMain()
Dim refname()
Dim reffullPath()
Dim refGUID()
ReDim refname(5)
refname() = Array("INFITF,MECMOD", "ProductStructureTypeLib")
ReDim reffullPath(5)
reffullPath() = Array("D:\opt\ds\catia\B28_VWGROUP\win_b64\code\bin\MecModTypeLib.tlb", "D:\opt\ds\catia\B28_VWGROUP\win_b64\code\bin\PSTypeLib.tlb")
ReDim refGUID(5)
refGUID() = Array("{0D90A5C9-3B08-11D1-A26C-0000F87546FD}", "{5065F8B6-61BB-11D1-9D85-0000F8759F82}")
CheckAndAddReference refname(), reffullPath(), refGUID()
End Sub
Sub CheckAndAddReference(refname() As Variant, refLocation() As Variant, refGUID() As Variant)
Set VBAEditorx = CreateObject("MSAPC.Apc").VBE 'Application.VBE
Set vbProj = VBAEditorx.ActiveVBProject 'ActiveWorkbook.VBProject
For j = 0 To UBound(refname)
For i = 1 To vbProj.References.Count
RefCon = False
If vbProj.References.Item(i).Name = refname(j) Then
RefCon = True
Exit For
End If
Next
If RefCon = False Then
vbProj.References.AddFromFile refLocation(j)
End If
Next
End Sub
the first line "Public oPart As Part" , I cant make it as Object because there are many of these in original program.
the above line requires a reference called "INFITF,MECMOD" which is not connected in some systems.
when I try to late bind it, it is showing the error as
Compile error:
user type not defined
so I wanted to ask weather i can late bind the reference while the line "Public oPart As Part" remains same in the code without showing an error.
or I need to make all the early bound objects into "As Object".